U.S. patent number 11,306,959 [Application Number 14/534,957] was granted by the patent office on 2022-04-19 for cooling systems and methods using two circuits with water flow in series and counter flow arrangement.
This patent grant is currently assigned to INERTECH IP LLC. The grantee listed for this patent is Inertech IP LLC. Invention is credited to John Costakis, Earl Keisling, Gerald McDonnell, Ming Zhang.
United States Patent |
11,306,959 |
McDonnell , et al. |
April 19, 2022 |
Cooling systems and methods using two circuits with water flow in
series and counter flow arrangement
Abstract
A cooling system is provided including a first evaporator coil
in thermal communication with an air intake flow to a heat load, a
first liquid refrigerant distribution unit in fluid communication
with the first evaporator coil to form a first fluid circuit, a
second evaporator coil disposed in series with the first evaporator
coil in the air intake flow and in the thermal communication with
the air intake flow to the heat load, a second liquid refrigerant
distribution unit in fluid communication with the second evaporator
coil to form a second fluid circuit, a water loop in thermal
communication with the first fluid circuit and second fluid
circuit, and a chiller loop in thermal communication with the water
loop.
Inventors: |
McDonnell; Gerald (Poughquag,
NY), Zhang; Ming (Ballwin, MO), Costakis; John (Hyde
Park, NY), Keisling; Earl (Ridgefield, CT) |
Applicant: |
Name |
City |
State |
Country |
Type |
Inertech IP LLC |
Danbury |
CT |
US |
|
|
Assignee: |
INERTECH IP LLC (Plano,
TX)
|
Family
ID: |
53494881 |
Appl.
No.: |
14/534,957 |
Filed: |
November 6, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20150192345 A1 |
Jul 9, 2015 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61900602 |
Nov 6, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B
25/005 (20130101); F25D 17/02 (20130101); F25B
1/005 (20130101); F25B 2339/047 (20130101); F25B
1/00 (20130101) |
Current International
Class: |
F25D
17/02 (20060101); F25B 25/00 (20060101); F25B
1/00 (20060101) |
Field of
Search: |
;62/335 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101442893 |
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CN |
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100584168 |
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CN |
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101686629 |
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Mar 2010 |
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CN |
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102334396 |
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Jan 2012 |
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CN |
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102461357 |
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May 2012 |
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CN |
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102012218873 |
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May 2013 |
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DE |
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1604263 |
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Dec 2005 |
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EP |
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2008287733 |
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Nov 2008 |
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JP |
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5113203 |
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Jan 2013 |
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JP |
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5209584 |
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Jun 2013 |
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JP |
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5243929 |
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Jul 2013 |
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JP |
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5244058 |
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Jul 2013 |
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5301009 |
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Sep 2013 |
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JP |
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5308750 |
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Oct 2013 |
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JP |
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Other References
E Stamper, R. Koral and C. Strock, Handbook of air conditioning,
heating, and ventilating. New York: Industrial Press, 1979. cited
by examiner .
Refrigeration Basics 101--Nelson, Eric--Dec. 24, 2012. cited by
examiner .
Heat Transfer/Heat Exchangers--Wikibooks--Aug. 11, 2011. cited by
examiner .
HP Modular Cooling System Site Preparation Guide, 2006-2007,
<http://h20565.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c00613-
691>. cited by applicant .
Air-Cooled High-Performance Data Centers: Case Studies and Best
Methods, 2006,
<http://www.intel.in/content/dam/www/public/us/en/documents/whit-
e-papers/date-center-efficiency-air-cooled-bkms-paper.pdf>.
cited by applicant .
Liebert Xtreme Density--System Design Manual, 2009,
<http://shared.liebert.com/SharedDocuments/LiebertFiles/SL_16655_REV09-
_07-09.pdf>. cited by applicant .
Data Center Evolution A Tutorial on State of the Art, Issues, and
Challenges, 2009,
<http://www.cse.iitb.ac.in/.about.puru/courses/autumn12/cs695/download-
s/dcevolve.pdf>. cited by applicant .
Weatherman: Automated, Online, and Predictive Thermal Mapping and
Management for Data Centers, 2006,
<http://www.cse.iitb.ac.in/.about.puru/courses/spring14/cs695/download-
s/weatherman.pdf>. cited by applicant .
Reduced-Order Modeling Of Multiscale Turbulent Convection:
Application to Data Center Thermal Management, May 2006,
<https://smartech.gatech.edu/bitstream/handle/1853/14605/rambo_jeffrey-
_200605_phd.pdf>. cited by applicant.
|
Primary Examiner: Sanks; Schyler S
Attorney, Agent or Firm: Weber Rosselli & Cannon LLP
Claims
What is claimed is:
1. A cooling system comprising: a first refrigerant circuit
including a first evaporator coil in thermal communication with an
air outtake flow to a heat load in a first condenser in fluid
communication with the first evaporator coil; a second refrigerant
circuit including a second evaporator coil in thermal communication
with an air intake flow from the heat load and a second condenser
in fluid communication with the second evaporator coil, the second
evaporator coil disposed in air flow series with the first
evaporator coil so that the air intake flow is fluidly coupled to
the air outtake flow, the second condenser arranged in series with
the first condenser so that the second condenser is in direct fluid
communication with the first condenser; a single water loop in
fluid communication with a free-cooling fluid cooler and in fluid
communication with the first condenser and the second condenser so
that water output from the free-cooling fluid cooler flows to the
second condenser directly from the first condenser; a single
chiller loop in thermal communication with the water loop and each
of the first and second condensers, the chiller loop including a
trim condenser in fluid communication with the chiller loop at a
first fluid path of the trim condenser and the water loop at a
second fluid path of the trim condenser; and a single air
conditioning system evaporator in thermal communication with each
of the first and second condensers, the single air conditioning
system evaporator having a first fluid path and a second fluid
path, the first fluid path of the air conditioning system
evaporator being in fluid communication with an outlet of the first
fluid path of the trim condenser and the second fluid path of the
air conditioning system evaporator being in fluid communication
with the water loop, wherein the second fluid path of the air
conditioning system evaporator is in fluid communication with the
second fluid path of the trim condenser via the first condenser and
the second condenser, and wherein the fluid flowing through the
chiller loop and a fluid flowing through the water loop flow in
opposite directions through the trim condenser.
2. The cooling system according to claim 1, wherein the first and
second evaporator coils are microchannel evaporator coils.
3. The cooling system according to claim 1, wherein the chiller
loop includes a compressor in fluid communication with a fluid
output of the first fluid path of the air conditioning system
evaporator and with a fluid input of the first fluid path of the
trim condenser.
4. The cooling system according to claim 3, wherein chilled water
from the air conditioning system evaporator is in thermal
communication with the first and second fluid circuits; and wherein
the chiller water and the refrigerant flowing through the first and
second fluid circuits are in thermal counter flow.
5. The cooling system according to claim 3, wherein water flow
through the trim condenser is in a series or in a parallel
arrangement with water flow through the air conditioning system
evaporator, the first condenser, and the second condenser.
6. A cooling system, comprising: a first refrigerant circuit
including a first evaporator coil in thermal communication with an
air outtake flow to a heat load and a first condenser in fluid
communication with the first evaporator coil; a second refrigerant
circuit including a second evaporator coil in thermal communication
with an air intake flow from the heat load and a second condenser
in fluid communication with the second evaporator coil, the second
evaporator coil disposed in air flow series with the first
evaporator coil so that the air intake flow is fluidly coupled to
the air outtake flow, the second condenser arranged in series with
the first condenser so that the second condenser is in direct fluid
communication with the first condenser; a single water loop in
fluid communication with a free-cooling fluid cooler and in fluid
communication with the first condenser and the second condenser so
that water output from the free-cooling fluid cooler flows to the
second condenser via the first condenser; a single chiller loop in
thermal communication with the water loop and each of the first and
second condensers, the chiller loop including: a single trim
condenser having a first fluid path and a second fluid path; a
single air conditioning system evaporator in thermal communication
with each of the first and second condensers, the single air
conditioning system evaporator having a first fluid path and a
second fluid path, the first fluid path of the air conditioning
system evaporator being in fluid communication with the first fluid
path of the trim condenser; and a compressor in fluid communication
with a fluid output of the first fluid path of the air conditioning
system evaporator and with a fluid input of the first fluid path of
the trim condenser, wherein the first refrigerant circuit includes
the first condenser having a first fluid path and a second fluid
path, a first fluid receiver in fluid communication with the first
fluid path of the first condenser, and a first refrigerant pump in
fluid communication with the first fluid receiver, the second fluid
path of the first condenser being in fluid communication with the
second fluid path of the air conditioning system evaporator,
wherein the second refrigerant circuit includes the second
condenser having a first fluid path and a second fluid path, a
second fluid receiver in fluid communication with the first fluid
path of the second condenser, a second refrigerant pump in fluid
communication with the second fluid receiver, the second fluid path
of the second condenser being in fluid communication with the
second fluid path of the first condenser and the water loop,
wherein the water loop is in fluid communication with the second
fluid path of the trim condenser, wherein water flows through the
air conditioning system evaporator to the trim condenser via the
first condenser and the second condenser, and wherein a fluid
flowing through the chiller loop and a fluid flowing through the
water loop flow in opposite directions through the trim
condenser.
7. The cooling system according to claim 4, wherein a refrigerant
saturation temperature of the first fluid circuit is less than a
refrigerant saturation temperature of the second fluid circuit.
8. The cooling system according to claim 3, wherein the first
refrigerant circuit further includes a first fluid receiver in
fluid communication with a first fluid path of the first condenser,
wherein the first refrigerant pump is in fluid communication with
the first fluid receiver, and wherein a second fluid path of the
first condenser is in fluid communication with the second fluid
path of the air conditioning system evaporator.
9. The cooling system according to claim 3, wherein the second
refrigerant circuit further includes a second fluid receiver in
fluid communication with a first fluid path of the second
condenser, wherein the second refrigerant pump is in fluid
communication with the second fluid receiver, and wherein a second
fluid path of the second condenser is in fluid communication with
the second fluid path of the first condenser and the water
loop.
10. The cooling system according to claim 6, wherein the first and
second evaporator coils are microchannel evaporator coils.
Description
BACKGROUND
Conventional cooling systems do not exhibit significant reductions
in energy use in relation to decreases in load demand. Air-cooled
direct expansion (DX), water-cooled chillers, heat pumps, and even
large fan air systems do not scale down well to light loading
operation. Rather, the energy cost per ton of cooling increases
dramatically as the output tonnage is reduced on conventional
systems. This has been mitigated somewhat with the addition of
fans, pumps, and chiller variable frequency drives (VFDs); however,
their turn-down capabilities are still limited by such issues as
minimum flow constraints for thermal heat transfer of air, water,
and compressed refrigerant. For example, a 15% loaded air
conditioning system requires significantly more than 15% power of
its 100% rated power use. In most cases such a system requires as
much as 40-50% of its 100% rated power use to provide 15% of
cooling work.
Conventional commercial, residential, and industrial air
conditioning cooling circuits require high electrical power draw
when energizing the compressor circuits to perform the cooling
work. Some compressor manufacturers have mitigated the power in
rush and spikes by employing energy saving VFDs and other
apparatuses for step loading control functions. However, the
current systems employed to perform cooling functions are extreme
power users.
Existing refrigerant systems do not operate well under partial or
lightly loaded conditions, nor are they efficient at low
temperature or "shoulder seasonal" operation in cooler climates.
These existing refrigerant systems are generally required to be
fitted with low ambient kits in cooler climates, and other energy
robbing circuit devices, such as hot gas bypass in order to provide
a stable environment for the refrigerant under these
conditions.
Compressors on traditional cooling systems rely on tight control of
the vapor evaporated in an evaporator coil. This is accomplished by
using a metering device (or expansion valve) at the inlet of the
evaporator which effectively meters the amount of liquid that is
allowed into the evaporator. The expanded liquid absorbs the heat
present in the evaporator coil and leaves the coil as a
super-heated vapor. Tight metering control is required in order to
ensure that all of the available liquid has been boiled off before
leaving the evaporator coil. This can create several problems under
low loading conditions, such as uneven heat distribution across a
large refrigerant coil face or liquid slugging to the compressor.
This latter scenario can damage or destroy a compressor.
To combat the inflexibility problems that exist on the low-end
operation of refrigerant systems, manufacturers employ hot gas
bypass and other low ambient measures to mitigate slugging and
uneven heat distribution. These measures create a false load and
cost energy to operate.
Conventional air-cooled air conditioning equipment is inefficient.
The kw per ton (kilowatt of electrical power per ton of
refrigeration or kilowatt of electrical power per 3.517 kilowatts
of refrigeration) for the circuits are more than 1.0 kw per ton
during operation in high dry bulb ambient conditions.
Evaporative assist condensing air conditioning units exhibit better
kw/ton energy performance over air-cooled DX equipment. However,
they still have limitations in practical operation in climates that
are variable in temperature. They also require a great deal more in
maintenance and chemical treatment costs.
Central plant chiller systems that temper, cool, and dehumidify
large quantities of hot process intake air, such as intakes for
turbine inlet air systems, large fresh air systems for hospitals,
manufacturing, casinos, hotel, and building corridor supply systems
are expensive to install, costly to operate, and are inefficient
over the broad spectrum of operational conditions.
Existing compressor circuits have the ability to reduce power use
under varying or reductions in system loading by either stepping
down the compressors or reducing speed (e.g., using a VFD). There
are limitations to the speed controls as well as the steps of
reduction.
Gas turbine power production facilities rely on either expensive
chiller plants and inlet air cooling systems, or high volume water
spray systems as a means to temper the inlet combustion air. The
turbines lose efficiency when the entering air is allowed to spike
above 15.degree. C. and possess a relative humidity (RH) of less
than 60% RH. The alternative to the chiller plant assist is a high
volume water inlet spray system. High volume water inlet spray
systems are less costly to build and operate. However, such systems
present heavy maintenance costs and risks to the gas turbines, as
well as consume huge quantities of potable water.
Hospital intake air systems require 100% outside air. It is
extremely costly to cool this air in high ambient and high latent
atmospheres using the conventional chiller plant systems.
Casinos require high volumes of outside air for ventilation to
casino floors. They are extremely costly to operate, and utilize a
tremendous amount of water especially in arid environments, e.g.,
Las Vegas, Nev. in the United States.
Middle eastern and desert environments have a high impact on inlet
air cooling systems due to the excessive work that a compressor is
expected to perform as a ratio of the inlet condensing air or water
versus the leaving chilled water discharge. The higher the delta,
the more work the compressor has to perform with a resulting higher
kw/ton electrical draw. As a result of the high ambient desert
environment, a cooling plant will expend nearly double the amount
of power to produce the same amount of cooling in a less arid
environment.
High latent load environments, such as in Asia, India, Africa, and
the southern hemispheres, require high cooling capacities to handle
the effects of high moisture in the atmosphere. The air must be
cooled and the moisture must be eliminated in order to provide
comfort cooling for residential, commercial, and industrial outside
air treatment applications. High latent heat loads cause
compressors to work harder and require a higher demand to handle
the increased work load.
Existing refrigeration process systems are normally designed and
built in parallel. The parallel systems do not operate efficiently
over the broad spectrum of environmental conditions. They also
require extensive control operating algorithms to enable the
various pieces of equipment on the system to operate as one
efficiently. There are many efficiencies that are lost across the
operating spectrum because the systems are piped, operated, and
controlled in parallel.
There have not been many innovations in air conditioning systems
and cooling equipment that address the inherent limitations of the
various refrigerant cooling processes. Each conventional system
exhibits losses in efficiency at high-end, shoulder, and low-end
loading conditions. In addition to the non-linear power versus
loading issues, environmental conditions have extreme impacts on
the individual cooling processes. The conventional systems are too
broadly utilized across a wide array of environmental conditions.
The results are that most of the systems operate inefficiently for
a vast majority of time. The reasons for the inefficiencies are
based on operator misuse, misapplication for the environment, or
losses in efficiency due to inherent limiting characteristics of
the cooling equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic flow diagram of a cooling system in
accordance with embodiments of the present disclosure.
FIG. 2 is a schematic flow diagram of an alternative embodiment of
the cooling system of FIG. 1.
DETAILED DESCRIPTION
The present disclosure features a cooling system for data centers
or for any other applications that have high heat rejection
temperature and high sensible heat ratio compared to general air
conditioning or refrigeration applications.
Some systems for data center cooling use two separate liquid
refrigerant pump systems. Each pump system has its own water-cooled
condenser, along with a chiller loop. The chiller loop includes a
fluid cooler, a compressor, a trim condenser, and an air
conditioning system (ACS) evaporator. When the outdoor ambient
temperature is high, the chiller loop cools water from the outdoor
fluid cooler. Further, if one of the two chiller loops fails to
operate, the other is used as a backup. If both chiller loops are
operable, the two of them can run in parallel for normal operation
to obtain higher cooling capacity and energy efficiency.
The cooling systems and methods according to the present disclosure
connect the water flow of the two chiller loop systems in a series,
counter-flow arrangement. This design, together with optimal flow
rate selection and control, significantly improves the system
energy efficiency and reduces water flow rate and pipe size.
Some cooling systems use two circuits, each of which has a
refrigerant pump loop and a water (or glycol) loop to condense the
refrigerant. The water can be chilled (or "trimmed") by a
compressor/chiller loop when the outdoor wet bulb temperature is
high. The two circuits have parallel water flow. In normal
operation, the two circuits work simultaneously, and the
evaporators for air cooling of the two circuits are in series, and
air from the high temperature circuit enters the evaporator of the
low temperature circuit to be cooled further.
If one of the two circuits fails to operate, the system operates in
"failure mode" or "backup mode" with only one circuit in operation.
The cooling system of the present disclosure employs two circuits,
but the water (or glycol) flows through the two circuits in series
and counter flow pattern, resulting in higher energy efficiency,
lower water flow rate, and a broader operating range, e.g., it can
run with a higher outdoor wet bulb temperature.
FIG. 1 is a schematic flow diagram of a cooling system in
accordance with embodiments of the present disclosure. As shown,
water (or glycol) from the fluid cooler is pumped first through the
ACS evaporator where it is chilled (when ambient or wetbulb
temperature is high), and then through main condenser 1 and main
condenser 2 of the two pumped refrigerant fluid circuits. From the
main condensers, the water (or glycol/water mixture) is mixed with
additional water from the outlet of the fluid cooler, and then goes
through the trim condenser and finally through the fluid cooler,
completing the cycle. Alternatively, the water from the main
condenser 2 is mixed with the water leaving the trim condenser at
the outlet of the trim condenser and returns to the fluid
cooler.
The two main pumped refrigerant fluid circuits are connected to
evaporators at or near the heat source (e.g., mounted on the rear
doors or tops of computer server cabinets or from the ceiling above
the cabinets to cool the electronic equipment). Air and water flow
of the two fluid circuits is in a counter flow arrangement: warm
air (e.g., 40.degree. C.) from electronic equipment is cooled in
the first evaporator to a lower temperature (e.g., 32.degree. C.),
and then air leaving fluid circuit 2 enters the evaporator of fluid
circuit 1 and is further cooled (e.g., to 25.degree. C.). In other
words, chilled water from the ACS evaporator is in thermal
communication with the first and second fluid circuits, and the
chilled water and the refrigerant flowing through the first and
second fluid circuits are in thermal counter flow: the chilled
water is first in thermal communication with the refrigerant with
lower temperature (corresponding to lower air temperature in the
evaporator) in fluid circuit 1 through the main condenser 1, with
its temperature raised, and then is in thermal communication with
the refrigerant with higher temperature (corresponding to higher
air temperature in the evaporator) in fluid circuit 2 through the
main condenser 2, with its temperature further raised. In
embodiments, the evaporators may include microchannel
evaporators.
The refrigerant saturation temperature of fluid circuit 1 is
maintained lower than fluid circuit 2 (e.g., 24.degree. C. for
fluid circuit 1 versus 31.degree. C. for fluid circuit 2); the
water (or glycol) from the fluid cooler or ACS evaporator with
lower temperature flows through main condenser 1 to condense
refrigerant vapor in fluid circuit 1, with its temperature raised,
and then flows through main condenser 2 to condense refrigerant
vapor in fluid circuit 2, with its temperature further raised, then
flows to the trim condenser. This flow arrangement plus optimal
water (or glycol) flow rate control can increase system energy
efficiency and significantly reduce water flow rate, pipe size and
pumping power.
The two refrigerant fluid circuits 1 and 2 shown in FIG. 1 can also
be used with a chiller plant. Chilled water from the chiller plant
flows through the main condenser 1 of the fluid circuit 1, and then
through the main condenser 2 of the fluid circuit 2, and then
returns to the chiller plant with a higher temperature. In other
words, the chiller plant may replace the water and chiller loops of
FIG. 1. Thus, the output of the chiller plant is provided to the
input of the water side of main condenser 1 and the output of the
water side of main condenser 2 is provided to the input of the
chiller plant. The chiller plant may provide chilled water to
multiple refrigerant distribution units including fluid circuits 1
and 2. Compared to conventional CRAC units, this design has a lower
water flow rate, and consumes much less pumping and compressor
power.
Although the illustrative embodiments of the present disclosure
have been described herein with reference to the accompanying
drawings, it is to be understood that the disclosure is not limited
to those precise embodiments, and that various other changes and
modification may be effected therein by one skilled in the art
without departing from the scope or spirit of the disclosure.
In embodiments, the water flow through the trim condenser and the
water flow through the ACS evaporator, the first main condenser,
and the second main condenser, may be in a series or in a parallel
arrangement. FIG. 1 shows the in series arrangement. The in
parallel arrangement is illustrated in FIG. 2 and may be formed by
disconnecting the output of the water side of main condenser 2 from
the fluid line or fluid conduit connected between the water pump
and the input to the water loop side of the trim condenser, and
connecting the output of the water side of main condenser 2 to the
fluid line or fluid conduit connected between the output of the
water loop side of the trim condenser and the input to the fluid
cooler.
Other applications for the cooling system of the present disclosure
include turbine inlet air cooling, laboratory system cooling, and
electronics cooling, among many others.
* * * * *
References